:root{--paper:#f6f5f1;--ink:#293330;--muted:#7b817c;--rule:#dcded5;--orange:#bf623d;--green:#557e6d;--blue:#527e9e;--serif:"Songti SC","STSong","Noto Serif CJK SC",serif;--sans:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",sans-serif}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:95px}body{margin:0;background:var(--paper);color:var(--ink);font-family:var(--sans);-webkit-font-smoothing:antialiased;font-size:16px}button,input,select{font:inherit}button,a,input,select{-webkit-tap-highlight-color:transparent}button{cursor:pointer}a{color:inherit;text-decoration:none}button{color:inherit}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,summary:focus-visible{outline:2px solid var(--orange);outline-offset:6px}.reading-progress{position:fixed;z-index:40;top:0;height:3px;background:transparent;width:100%}.reading-progress div{height:100%;background:var(--orange);width:0}.site-header{max-width:1380px;margin:auto;height:94px;padding:0 48px;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--rule)}.brand{display:flex;align-items:center;gap:12px;font-size:16px;font-weight:600;letter-spacing:2px}.brand svg{width:29px;height:29px;stroke:var(--orange);fill:none;stroke-width:1.45}.brand-sub{color:var(--muted);font-weight:400}.brand-separator{margin:0 10px;color:#a4a89f;font-weight:400}.header-actions{display:flex;align-items:center;gap:28px;font-size:12px}.edition{color:var(--muted);letter-spacing:1px}.text-button{border:0;background:none;padding:9px 0;font-size:12px}.pause-icon{font-weight:bold;margin-right:3px;color:var(--orange)}.mobile-toc{display:none}.contents{position:fixed;left:max(28px,calc((100vw - 1430px)/2));top:170px;width:138px;display:flex;flex-direction:column;gap:3px;z-index:20}.contents-title{font-size:10px;letter-spacing:3px;color:var(--muted);margin:0 0 17px 0}.contents a{font-size:11px;padding:8px 0;color:#90958d;white-space:nowrap;transition:color .2s}.contents a span{display:inline-block;width:25px;font-size:10px;font-variant-numeric:tabular-nums;opacity:.65}.contents a:hover,.contents a.active{color:var(--orange)}.contents a.active{font-weight:600}.contents-bottom{font-size:9px;color:#a0a69c;margin-top:30px;letter-spacing:1.5px}main{max-width:1032px;margin:0 auto;padding:0 32px}.intro{padding-top:50px}.intro-meta{display:flex;justify-content:space-between;font-size:11px;letter-spacing:1.5px;color:var(--muted)}.intro-meta i{display:inline-block;width:6px;height:6px;background:var(--orange);border-radius:50%;margin-right:9px;vertical-align:2px}.intro-heading{display:flex;align-items:flex-end;justify-content:space-between;margin-top:42px;margin-bottom:26px}h1{font-size:82px;font-weight:500;line-height:1.2;letter-spacing:-4px;margin:0}.accent{color:var(--orange)}.intro-copy{width:285px;padding-bottom:7px}.intro-copy p{font-size:15px;line-height:1.9;letter-spacing:.3px;margin:0 0 26px;color:#69736c}.down-link{font-size:12px;display:flex;gap:35px;width:max-content;align-items:center}.down-link span{color:var(--orange);font-size:21px}.car-figure{margin:48px -12px 0}.figure-topline{border-top:1px solid var(--rule);padding:18px 0;display:flex;align-items:center;justify-content:space-between;gap:15px;color:var(--muted);font-size:11px;letter-spacing:.7px}.figure-number{font-size:10px;color:var(--orange);margin-right:18px;letter-spacing:1px}.car-model{height:530px;position:relative;touch-action:pan-y;isolation:isolate}.car-model canvas{display:block;width:100%;height:100%;cursor:grab;touch-action:none}.car-model canvas:active{cursor:grabbing}.model-loading{position:absolute;inset:0;display:flex;flex-direction:column;justify-content:center;align-items:center;gap:14px;font-size:14px;color:var(--muted)}.model-loading span{font-size:11px;letter-spacing:2px}.model-instructions{display:flex;align-items:center;justify-content:space-between;margin-top:-6px;font-size:11px;color:var(--muted);padding-bottom:15px}.model-instructions>span{display:flex;align-items:center;gap:7px}.model-instructions svg{width:18px;height:18px;fill:none;stroke:currentColor;stroke-width:1}.mini-button{border:0;background:transparent;color:var(--muted);font-size:11px;padding:8px 0 8px 18px}.mini-button[aria-pressed=true]{color:var(--orange)}.model-controls{display:flex;align-items:center;gap:35px;border-top:1px solid var(--rule);border-bottom:1px solid var(--rule);padding:22px 0}.explosion-control{width:310px;flex-shrink:0}.explosion-control>div{display:flex;justify-content:space-between;font-size:12px}.explosion-control output{font-variant-numeric:tabular-nums;color:var(--orange);font-size:11px}.range-ends{font-size:9px!important;color:var(--muted);margin-top:6px}.layer-controls{display:flex;justify-content:flex-end;gap:3px;flex-wrap:wrap;flex:1}.layer-controls button,.system-tabs button{border:1px solid transparent;background:none;font-size:11px;padding:9px 11px;border-radius:4px;display:flex;align-items:center;gap:5px;white-space:nowrap;color:#7b827a;transition:all .15s}.layer-controls .selected{background:#e7e9e0;border-color:#dce0d3;color:#34463a}.dot{width:5px;height:5px;display:inline-block;border-radius:50%}.orange{background:var(--orange)}.blue{background:var(--blue)}.green{background:var(--green)}input[type=range]{--fill:35%;-webkit-appearance:none;appearance:none;height:3px;border-radius:4px;background:linear-gradient(to right,var(--orange) 0,var(--orange) var(--fill),#d6d9ce var(--fill),#d6d9ce 100%);cursor:pointer;width:100%;margin:18px 0 10px;display:block}input[type=range]::-webkit-slider-thumb{-webkit-appearance:none;width:14px;height:14px;background:var(--paper);border:2px solid var(--orange);border-radius:50%;box-shadow:0 0 0 4px var(--paper)}input[type=range]::-moz-range-thumb{width:11px;height:11px;background:var(--paper);border:2px solid var(--orange);border-radius:50%}figcaption{font-size:11px;color:#82887f;line-height:1.85;letter-spacing:.1px;max-width:730px;margin:15px auto 0;text-align:center}.car-figure figcaption{margin-top:16px;max-width:760px}.prose{max-width:668px;margin-left:auto;margin-right:auto}.prose p{font-size:16px;line-height:2.1;letter-spacing:.2px;margin:22px 0;color:#566158}.prose strong{font-weight:600;color:#35483c}.introduction{margin-top:70px}.energy-strip{display:flex;align-items:center;justify-content:space-between;margin:52px auto 20px;max-width:815px;padding:26px 20px;border-top:1px solid var(--rule);border-bottom:1px solid var(--rule)}.energy-strip div{display:flex;flex-direction:column;text-align:center;gap:8px}.energy-strip div>span{font-size:9px;letter-spacing:3px;color:#959c92}.energy-strip strong{font-size:16px;font-weight:500}.energy-strip small{font-size:10px;color:var(--muted)}.energy-strip b{font-weight:300;color:#a4ac9e;font-size:22px}.orange-text{color:var(--orange)!important}.blue-text{color:var(--blue)!important}.green-text{color:var(--green)!important}.chapter{padding-top:110px;scroll-margin-top:10px}.chapter-kicker{font-size:13px;color:var(--orange);letter-spacing:2px;display:flex;gap:15px;align-items:center;margin-bottom:22px}.chapter-kicker:after{content:'';width:34px;height:1px;background:#d6c7b9}.chapter-kicker span{font-size:10px;color:#878d83;letter-spacing:2px}h2{font-size:31px;font-weight:500;letter-spacing:-.6px;line-height:1.5;margin:0 0 28px}h3{font-size:20px;font-weight:500;margin-top:40px;line-height:1.7}.term{font-weight:600}.demo,.system-figure,.structure-figure{max-width:850px;margin:40px auto 38px}.demo canvas{width:100%;height:400px;display:block}.demo .figure-topline{padding:17px 10px}.live-readout{color:var(--orange);min-width:45px}.demo-controls{display:flex;align-items:center;gap:25px;border-top:1px solid var(--rule);padding:20px 26px 12px;min-height:76px}.play-button{border:1px solid #d5dbcf;background:transparent;font-size:11px;border-radius:50px;min-width:65px;padding:9px 14px}.play-button:hover{border-color:#9ba890}.range-control{display:flex;align-items:center;gap:20px;font-size:11px;flex:1;white-space:nowrap}.range-control input[type=range]{flex:1;min-width:40px;margin:10px 0}.range-control output{font-variant-numeric:tabular-nums;min-width:48px;text-align:right;color:var(--orange)}.range-end{font-size:10px;color:var(--muted)}.double-controls{gap:40px}.metrics{display:flex;justify-content:center;gap:80px;margin:6px 0 25px}.metrics>div{display:flex;flex-direction:column;gap:8px;text-align:center}.metrics>div>span{font-size:10px;color:var(--muted);letter-spacing:1px}.metrics strong{font-size:24px;font-weight:400;color:var(--blue);font-variant-numeric:tabular-nums}.metrics small{font-size:10px;color:var(--muted);font-weight:400}.metrics.two{gap:140px}.steps{margin:40px 0 24px;display:grid;grid-template-columns:1fr 1fr;gap:24px 30px}.steps>div{display:flex;gap:14px}.steps>div>span{color:var(--orange);font-size:20px;padding-top:2px}.steps p{margin:0;font-size:13px;line-height:1.9}.steps strong{display:block;font-size:14px;margin-bottom:5px}.prose details{margin:30px 0;border-top:1px solid var(--rule);border-bottom:1px solid var(--rule)}summary{list-style:none;cursor:pointer;font-size:13px;padding:20px 0;display:flex;justify-content:space-between;align-items:center;color:#4e6052}summary::-webkit-details-marker{display:none}summary>span{font-size:18px;font-weight:300;color:#8e9889;transition:transform .2s}details[open] summary>span{transform:rotate(45deg)}details p{font-size:13px!important;margin:0 0 24px!important;line-height:1.9!important}.note{border-left:2px solid #a5b4a0;padding:6px 0 6px 25px;margin:36px 0}.note>span{font-size:11px;letter-spacing:1px;color:var(--green)}.note p{font-size:14px;margin:10px 0 0;line-height:2}.system-tabs{display:flex;justify-content:center;gap:18px;padding-top:20px}.system-tabs button{border-radius:0;border-bottom:1px solid transparent}.system-tabs button.selected{color:var(--orange);border-bottom-color:var(--orange)}.system-figure>svg{width:100%;height:auto;display:block;margin:6px 0}.system-caption{max-width:610px;margin:auto;padding:0 20px}.system-caption strong{font-weight:500;font-size:14px}.system-caption p{font-size:13px;line-height:1.95;color:var(--muted);margin:12px 0 0}.system-figure svg text{font-family:var(--sans);font-size:13px}.system-figure svg .flow-path{stroke-dasharray:7 7;animation:flow 2s linear infinite}@keyframes flow{to{stroke-dashoffset:-56}}.paused .flow-path{animation-play-state:paused!important}.structure-figure svg{display:block;width:100%;height:auto;padding-top:15px}.structure-figure text{font-family:var(--sans);font-size:13px;letter-spacing:.6px}.control-flow{max-width:840px;display:grid;grid-template-columns:1fr 30px 1fr 30px 1fr;gap:10px;margin:50px auto 40px;position:relative;padding-bottom:70px}.control-flow>div:not(.feedback-line){text-align:center;padding:18px 5px;border-top:1px solid #cfd7cb}.control-flow small{font-size:10px;color:var(--muted);letter-spacing:3px;display:block}.control-flow h3{font-size:17px;margin:10px 0}.control-flow p{font-size:12px;line-height:1.9;color:var(--muted);margin:0}.flow-symbol{font-size:31px;color:var(--green);display:block;margin:6px 0 12px}.flow-arrow{color:#99a68e;align-self:center;margin-top:-60px}.feedback-line{position:absolute;bottom:4px;left:16%;right:16%;height:35px;border:1px solid #bdcbb4;border-top:0;text-align:center;color:#819776;font-size:10px}.feedback-line span{background:var(--paper);position:relative;top:27px;padding:0 14px;letter-spacing:2px}.electric-controls>label:first-child{font-size:11px;display:flex;gap:10px;align-items:center}select{font-size:11px;background:transparent;color:var(--green);border:1px solid #cbd6c5;padding:7px 25px 7px 10px;border-radius:3px}.comparison{overflow-x:auto;max-width:850px;margin:45px auto 0}table{border-collapse:collapse;width:100%;font-size:12px;text-align:left;min-width:600px}caption{text-align:left;font-size:11px;color:var(--muted);letter-spacing:1px;margin-bottom:18px}th,td{padding:17px 16px;border-bottom:1px solid var(--rule);line-height:1.7}thead{color:var(--green);background:#ecefe7}th{font-weight:500}tbody th{color:#808d79}td{color:#63705f}.finale{padding-top:140px}.finale h2{font-family:var(--serif);font-size:32px;line-height:1.7}.return-link{display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid #6a7d62;padding:20px 0;margin-top:40px;color:var(--green);font-size:13px}.return-link span{font-size:25px}.sources{border-top:1px solid var(--rule);margin-top:110px;padding-top:35px;padding-bottom:65px}.sources h2{font-size:13px;letter-spacing:1px;margin-bottom:10px}.sources p,.sources li{font-size:11px;line-height:1.9;color:#8b9385}.sources ul{list-style:none;padding:0;margin-top:20px}.sources li{margin:8px 0}.sources a{color:#61775b;text-decoration:underline;text-decoration-color:#c5d0be;text-underline-offset:4px}.site-footer{border-top:1px solid var(--rule);max-width:1284px;margin:auto;padding:28px 0 35px;display:flex;align-items:center;justify-content:space-between}.site-footer .brand{font-size:12px;letter-spacing:1px}.site-footer>span{font-family:var(--serif);font-size:13px;color:#91998b;letter-spacing:2px}.site-footer>a:last-child{font-size:10px;color:#7a8873}.skip-link{position:fixed;top:-80px;left:20px;background:var(--ink);color:white;padding:12px;z-index:99}.skip-link:focus{top:20px}
@media(min-width:1400px){main{margin-left:calc(50% - 440px)}}
@media(max-width:1399px){.contents{display:none}.site-footer{margin:0 48px}main{max-width:1020px}}
@media(max-width:900px){.site-header{padding:0 25px;height:78px}.edition{display:none}main{padding:0 28px}.intro{padding-top:40px}h1{font-size:70px}.intro-heading{margin-top:36px}.intro-copy{width:240px}.intro-copy p{font-size:13px}.car-model{height:460px}.model-controls{gap:25px}.explosion-control{width:260px}.layer-controls button{padding:7px 9px}.demo canvas{height:360px}.chapter{padding-top:90px}.double-controls{flex-direction:column;gap:18px}.double-controls label{width:100%}.contents.open{display:flex;background:var(--paper);position:fixed;top:78px;right:0;left:auto;bottom:0;width:230px;padding:28px;border-left:1px solid var(--rule);box-shadow:-20px 20px 60px #29333015;overflow-y:auto}.mobile-toc{display:block}.header-actions{gap:20px}.model-controls{align-items:stretch}.energy-strip{padding:22px 10px}.system-tabs{gap:5px}.metrics{gap:55px}}
@media(max-width:600px){html{scroll-padding-top:30px}.site-header{height:72px;padding:0 20px}.brand{font-size:13px;gap:8px;letter-spacing:1px}.brand svg{width:23px;height:23px}.brand-separator{margin:0 5px}.brand-sub{font-size:11px}.header-actions{gap:14px}.header-actions button{font-size:10px}.header-actions .pause-icon{display:none}main{padding:0 23px}.intro{padding-top:28px}.intro-meta{font-size:9px;letter-spacing:.6px;align-items:center}.intro-meta>span:last-child{font-size:8px}.intro-heading{margin-top:32px;gap:20px;align-items:center}h1{font-size:52px;letter-spacing:-3px;line-height:1.28}.intro-copy{width:145px;flex-shrink:0;padding-bottom:0}.intro-copy p{font-size:10px;line-height:1.95;letter-spacing:0;margin-bottom:20px}.desktop-break{display:none}.down-link{font-size:10px;gap:20px}.down-link span{font-size:17px}.car-figure{margin-top:30px;margin-left:-13px;margin-right:-13px}.figure-topline{font-size:9px;gap:8px;padding:14px 7px;letter-spacing:0}.figure-number{font-size:8px;margin-right:9px}.car-model{height:310px}.model-instructions{font-size:9px;padding:0 5px 10px;gap:4px}.model-instructions svg{width:15px;height:15px}.mini-button{font-size:9px;padding:7px 4px 7px 8px}.model-controls{flex-direction:column;padding:18px 12px 12px;gap:17px}.explosion-control{width:100%}.explosion-control>div{font-size:11px}.layer-controls{justify-content:space-between;gap:2px}.layer-controls button{padding:8px;font-size:10px}.car-figure figcaption{font-size:9px;padding:0 14px;line-height:1.9}.introduction{margin-top:45px}.prose p{font-size:14px;line-height:2.05;margin:19px 0;letter-spacing:.05px}.energy-strip{margin-top:35px;padding:20px 0}.energy-strip strong{font-size:12px}.energy-strip small{font-size:8px}.energy-strip div>span{font-size:8px;letter-spacing:2px}.energy-strip b{font-size:16px}.chapter{padding-top:76px}.chapter-kicker{margin-bottom:18px;font-size:11px}.chapter-kicker span{font-size:9px}h2{font-size:24px;letter-spacing:-.7px;line-height:1.55;margin-bottom:21px}h3{font-size:18px;margin-top:30px}.demo,.system-figure,.structure-figure{margin:30px -13px}.demo canvas{height:285px}.demo .figure-topline{font-size:9px;padding:14px 6px}.demo-controls{padding:18px 9px 8px;gap:15px;min-height:65px}.range-control{font-size:10px;gap:12px}.range-control output{font-size:10px;min-width:40px}.play-button{min-width:53px;font-size:10px;padding:8px 10px}.range-end{font-size:9px}.demo figcaption,.structure-figure figcaption{font-size:9px;line-height:1.85;margin:15px 12px 0}.steps{gap:20px 22px;margin-top:28px}.steps>div{gap:9px}.steps>div>span{font-size:16px}.steps p{font-size:12px;line-height:1.9}.steps strong{font-size:13px}.metrics{gap:32px;margin:0 0 20px}.metrics strong{font-size:20px}.metrics>div>span{font-size:9px}.metrics small{font-size:8px}.metrics.two{gap:70px}.note{padding-left:18px;margin:28px 0}.note p{font-size:12px}.note>span{font-size:10px}summary{font-size:11px;padding:17px 0}details p{font-size:12px!important}.system-tabs{padding-top:10px;gap:0}.system-tabs button{font-size:10px;padding:8px 11px}.system-caption{padding:0 16px}.system-caption strong{font-size:12px}.system-caption p{font-size:11px}.system-figure svg text{font-size:17px}.structure-figure svg{padding:15px 0}.structure-figure text{font-size:15px}.control-flow{grid-template-columns:1fr 12px 1fr 12px 1fr;gap:5px;margin:30px 0;padding-bottom:60px}.control-flow h3{font-size:13px;margin:10px 0}.control-flow p{font-size:9px;line-height:1.8}.control-flow small{font-size:9px;letter-spacing:1px}.control-flow>div:not(.feedback-line){padding:12px 0}.flow-symbol{font-size:25px}.flow-arrow{font-size:13px}.feedback-line{left:13%;right:13%;font-size:9px}.electric-controls{flex-direction:column;align-items:stretch;gap:20px}.electric-controls>label:first-child{justify-content:space-between;font-size:10px}.electric-controls select{width:65%;font-size:10px}.comparison{margin:30px -2px 0}table{font-size:11px;min-width:600px}th,td{padding:14px}.finale{padding-top:95px}.finale h2{font-size:26px}.return-link{font-size:12px;margin-top:28px}.sources{margin-top:70px;padding-bottom:45px}.sources p,.sources li{font-size:10px}.sources h2{font-size:12px}.site-footer{margin:0 23px;padding:24px 0;gap:14px}.site-footer .brand{font-size:11px}.site-footer>span{display:none}.site-footer>a:last-child{font-size:9px}.contents.open{top:72px}}
@media(max-width:380px){main{padding:0 18px}h1{font-size:46px}.intro-copy{width:132px}.intro-meta{font-size:8px}.intro-meta>span:last-child{font-size:7px}.layer-controls button{padding:7px}.demo canvas{height:265px}.metrics{gap:24px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*:before,*:after{animation-duration:.01ms!important;animation-iteration-count:1!important;transition:none!important}}
@media print{.contents,.header-actions,.model-controls,.model-instructions,.demo-controls,.system-tabs{display:none}body{background:#fff}.site-header{padding:0}.intro{padding-top:25px}.chapter{padding-top:30px}.demo,.system-figure,.structure-figure{break-inside:avoid}a{color:inherit}.sources{margin-top:40px}main{max-width:100%;padding:0}.site-footer{margin:0}}
/* 持续可用的阅读导航 */
.site-header{position:sticky;top:0;z-index:30;background:rgba(246,245,241,.96);backdrop-filter:blur(12px)}
@media(max-width:1399px){.mobile-toc{display:block}.contents.open{display:flex;background:var(--paper);position:fixed;top:94px;right:0;left:auto;bottom:0;width:230px;padding:28px;border-left:1px solid var(--rule);box-shadow:-20px 20px 60px #29333015;overflow-y:auto}.contents.open a{font-size:12px;padding:9px 0}}
@media(max-width:900px){.contents.open{top:78px}}
@media(max-width:600px){.contents.open{top:72px}}
.play-button:disabled{color:#8b9386;cursor:default;background:#edefe6}
@media print{.site-header{position:static}}
